In recent years, touch panels are increasingly employed in operation input devices in use of, for example, electronic equipments. In the automobile field, it is conceivable that mechanical switch devices equipped to instrument panels for operating airconditioner apparatuses and navigation devices are to be replaced with touch sensors in future. Conventionally, it is difficult to cause an operation feeling, such as a click feeling, on existing touch panels and existing touch sensors, in response to a touch operation thereto. Accordingly, further amenity and certainty are demanded in operation of such devices. More specifically, in an operation input device including, for example, a touch panel configured to accept a touch operation thereto, it is demanded to apply a tactile feeling (tactile feedback) in response to a touch operation in order to enhance its operability.
For example, US 2010/0156814 A1 (JP-A-2010-152889) discloses a portable electronic device including a touch detection display. The portable electronic device of US 2010/0156814 A1 moves the touch detection display in response to a touch operation thereby to provide a tactile feedback. Specifically, the touch detecting display is movable relative to the housing, and the rear side of the touch detecting display is equipped with a piezoelectric actuator. Furthermore, in response to the touch operation, the piezoelectric actuator controls movement of the touch detecting display in the vertical direction according to the external force applied to the touch detecting display, thereby to simulate depression and release of a switch device.
For example, JP-A-2003-58321 discloses a touch panel device configured to oscillate its touch panel in the two-dimensional direction along its screen surface in various vibration patterns, when receiving a touch operation, thereby to provide various kinds of information to an operator with a tactile sense through the touch-panel screen. Specifically, the touch panel device of JP-A-2003-58321 includes a horizontal direction moving unit for moving the touch panel in the horizontal direction of the screen and a vertical direction moving unit for moving the touch panel in the vertical direction of the screen. The touch panel device of JP-A-2003-58321 controls the timing, when activating the horizontal direction moving unit and the vertical direction moving unit, and the moving speed and the movement (movement quantity) of the horizontal direction moving unit and the vertical direction moving unit, thereby to generate various vibration patterns.
JP-A-2004-58695 discloses a vibration device configured to cause a vibration, when receiving a touch operation, in an optimal vibration pattern including its acceleration and its frequency to cause a user to sense the vibration and not to feel discomfort.
In consideration of requirement of the operation performance of the touch-sensing operation input device in future, it is conceivable to simulate a tactile feeling further accurately when a mechanical switch device is operated. Specifically, it is conceivable to simulate a tactile feeling in consideration of a hardness of a switch device, such as a switch device of hard tactile feeling and a switch device of soft tactile feeling. Each of the above-described arts in US 2010/0156814 A1, JP-A-2003-58321, and JP-A-2004-58695 is configured to apply a tactile feeling in response to a touch operation. Nevertheless, each of these arts does not have a configuration to apply a tactile feeling in consideration of the hardness of a switch device. Therefore, the conventional configuration may apply an unexpected tactile feeling, such as a hard tactile feeling with respect to user's expectation of a soft tactile feeling.